To make sauce, heat oil in a saucepan over a medium heat. Add onion. Cook, stirring for 3 minutes or until golden. Add tomatoes. Cook, stirring for a further 2 minutes. Stir in tomato paste, cream, wine and basil. Bring to simmering and simmer, stirring frequently, for 10 minutes or until sauce reduces and thickens. Keep warm.

Score fish several times on both sides. Combine garlic, black peppercorns and salt in a bowl. Rub mixture over fish and shake off excess. Heat oil in a wok over a high heat until a cube of bread dropped in browns in 50 seconds. Cook fish, one at a time, for 3 minutes each side or until flesh flakes when tested with a fork. Drain on absorbent kitchen paper and keep warm. Deep fry leeks for 2 minutes or until golden. Drain on absorbent kitchen paper.

To serve, place fish on serving plates, top with the leeks, accompany with the sauce.